The present invention relates to a device for shaping a film of heat-retractable plastics material covering the lateral spaces for gripping a pallet-less multi-layer load having a layer of reduced thickness, these spaces for gripping being defined by right-angled dihedrons.
It is presently known to form pallet-less multi-layer loads from a plurality of articles stacked one on the other so as to form a substantially parallelepipedic assembly. These articles, which are, in particular, bags containing products (for example bags of cement), are grouped in superposed layers, each layer having a square or rectangular horizontal form. For forming a load without a pallet, a layer of reduced width is provided at the upper or lower part of the load, during stacking, said "reduced layer" being constituted by fewer articles and defined by a smaller square or rectangular geometrical surface than the peripheral surface of the normal layers. Consequently, the reduced layer defines, with the normal layer on or under which it is formed, two lateral empty spaces parallel to each other and in the form of right-angled dihedrons. The vertical side of each of these dihedrons is constituted by a lateral face of the reduced layer, whilst the horizontal side of this dihedron is formed by the portion of horizontal surface of the adjacent normal layer which remains exposed.
The lateral spaces thus defined by the reduced layer are used to enable the load to be gripped by a fork lift truck or by slings.
Once the load is thus formed with its reduced layer, it is packed beneath a film of plastics material, using several possible techniques (double wrapping, single or double covering . . . ). After the load has been packed, it is passed in a retraction oven. On leaving this oven, the plastics material, which is still hot, is softened and this softening is used to ensure shaping of the film so that it follows as closely as possible the faces of the dihedrons defining the spaces for gripping. This shaping is effected by mechanically pressing the soft plastics material by means of metal shaping elements.
Proper shaping must enable the plastics material to be definitively fixed, i.e. without its expanding when the shaping elements are withdrawn.